If you’ve seen your fair share of science fiction movies or TV shows or read any of the great sci-fi authors — you’ve probably come across the notion of time travel. The ability to escape the present and visit people and places in the distant past or future.
Imagine seeing the French revolution play out with your own eyes, talking to and hearing from people who were there, or simply seeing what the world will be like in a few centuries.
Is it sheer fantasy, or is it possible — at least theoretically? Below we consider some ways in which we might be able to travel into the future, or partake in the past.
Travelling into the future:
Want to travel 200 years into the future so you can see if we ever made it past climate change? Or maybe you just want to see what a Cheeseburger will taste like in 2220.
Here are three ways it is theoretically possible to do this:
1. Entering stasis
This basically involves hitting “pause” on your life for a period of time.
There are two variants of this:
Suspended animation: Your body temperature heart rate is slowed down, and perhaps even your blood is replaced. When the time comes to re-animate you, your blood is replaced and your temperature is brought back to normal. This has been done successfully with dogs and pigs.
Cryogenics: This basically involves freezing your brain — leaving it on ice for a couple of centuries, then putting into a new body (perhaps cloned from your own DNA). The brain freezing part can be done for mere tens of thousands of dollars, and is projected to cost less than your typical funeral in the near future.
2. Travelling at the speed of light
We know from physics’ that the theory of special relativity dictates that when objects travel at speeds approaching the speed of light — time itself slows down.
This means that if you get onto some sort of space ship that is travelling at the speed of light — you will not feel much time has passed (and thus not age) whilst on the ship even though decades or centuries might have passed for everyone back on earth. This is basically the plot of the 1986 movie Flight of the Navigator.
While we can’t travel at the speed of light just yet, we do however have technology such as propulsion based on ion discharge or nuclear fission that can start to achieve speeds that are considerable fractions of the speed of light. As technology advances, this will only increase.
3. Orbit a black hole and experience gravitational time dilation
Imagine a piece of paper held horizontally in the air — with both ends of the paper held in your hands. Let this paper represent “space-time”.
Now place a marble in the centre of this paper. The paper will sag in the middle — creating a depression. This marble (which in this scenario represents a black hole) is obviously a heck of a lot heavier than the paper (space-time) on which it sits, and therefore warps the paper around it.
Heavy mass in centre warps space around it
In a similar way, if you were to get into a spaceship and hang around near enough to a black hole — space-time will be warped around you such that time will pass relatively more slowly for you than those further away from the blackhole’s influence. Staying in this space ship for what might seem like a few hours might see decades or even centuries pass for people back home on Earth. This is effectively the plot of the Hollywood blockbuster Interstellar.
It would be a tricky thing though — you need to be close enough to the black hole to “benefit” from the effects of time dilation, but either somehow be shielded or far enough away to avoid being stretched out and torn apart (known as spaghettification)!
Travelling into the past:
This is a lot trickier conceptually. We might not be able to “travel” to the past as such, but there are ways we can experience or interact with it.
4. Using wormholes
Wormholes connect two points in space-time. The mouths of these two points could open into different years.
We might discover some that exist naturally, or perhaps one day, we might even be able to create wormholes ourselves (it is theoretical right now).
To enable time travel we could place one of the open mouths in Times Square in New York City. You’d then take the other open mouth of the wormhole, put it on a spaceship, and have said ship start travelling at the speed of light for what would be for us back on earth — a period of, let’s say 500 years.
When the ship finally comes to a stop around the year 2520; people from that time (including the ship’s crew) could walk back into the wormhole and return back to our current time.
To make it even more useful — as the ship travels at the speed of light in the above example, you could have them drop out of light speed every “10 years”, create another new wormhole with one mouth opening in various cities around the earth (so London can have an opening in 2029, Beijing in 2039, Sydney in 2049, etc), and have the other mouth being taken on board the space ship all the way through to 2519.
When the ship stops for the last time — it will have 50 odd wormhole mouths on board, each linking back to a different point in time right up until 2020.
Almost like a time-travelling version of an interconnecting train station or airport.
The limitation with this approach is that you cannot travel back in time earlier than the first of these wormholes. Unless of course we find a naturally occurring wormhole that links to some point in the past, stabilise it (they are thought to be highly unstable) and enlarge it sufficiently (they’re thought to typically be microscopic).
Getting ahead of light emanating from Earth
Look up at the sun — what you’re seeing is the sun as it was 8 minutes ago, the amount of time it took the rays of light from the sun to traverse through space, through the clouds and into your eyes.
Similarly — when we look up into the night sky, some of the galaxies and stars we see are actually what they were like millions of years ago — potentially no longer being around.
Now, an observer looking at Earth via a telescope on some planet 100 million light-years away doesn’t see Donald Trump in the Whitehouse, but a planet full of dinosaurs. That is because the light that left 100 million years ago has only just reached this alien observer’s telescope.
In this way, if you were able to “get-in front-of” the lightwaves being emanated from the Earth, you would be able to look back into the Earth’s past and see history happen in front of your eyes.
If you could get in front of lightwaves which left Earth 100 years ago, you’d be able to see Earth in 1919. If you could get in front of lightwaves which left Earth 2000 years ago, you could probably see what was going on in the Roman Empire.
As to how you could actually get ahead of these rays of light — I’m thinking wormholes might be handy, unless you have any better ideas?
If you’ve seen your fair share of science fiction movies or TV shows or read any of the great sci-fi authors — you’ve probably come across the notion of time travel. The ability to escape the present and visit people and places in the distant past or future.
Imagine seeing the French revolution play out with your own eyes, talking to and hearing from people who were there, or simply seeing what the world will be like in a few centuries.
Is it sheer fantasy, or is it possible — at least theoretically? Below we consider some ways in which we might be able to travel into the future, or partake in the past.
3. Orbit a black hole and experience gravitational time dilation
Wormholes connect two points in space-time. The mouths of these two points could open into different years.
Wormholes connect two points in space-time. The mouths of these two points could open into different years.
